Exhaust gas particulate filters have become common place emissions control equipment in many of today's vehicles and especially in vehicles powered by compression ignition engines. Exhaust gas particulate filters, frequently referred to as a diesel particulate filters (DPF) when used to control the emissions of a compression ignition diesel engine, are typically mounted in fluid communication with a vehicle's exhaust system. The exhaust gas particulate filter functions to remove unburned hydrocarbons or soot from the exhaust gas passing through the exhaust system before it exits the exhaust system and enters the environment. The soot that is removed from the exhaust gas by the exhaust gas particulate filter is trapped within a housing of the exhaust gas particulate filter. Over time, this soot builds up and must be removed. Rather than requiring dealer maintenance of the exhaust gas particulate filter and physical cleaning out of the housing, exhaust aftertreatment systems have been developed that elevate the temperature of the exhaust in the exhaust gas particulate filter such that the soot can burn off. These systems are commonly described as providing particulate filter regeneration through the burn off and attendant removal of soot.
Exhaust gas temperatures in the exhaust gas particulate filter can be raised through the injection of hydrocarbon fuel into the exhaust system or the exhaust gas particulate filter itself. The hydrocarbon fuel that is injected into the exhaust gas ignites raising the temperature of the exhaust gas to a temperature where the soot can burn off, pass through the exhaust gas particulate filter, and exit the exhaust system. Electronic control systems may be used to control a hydrocarbon injection system, which may also be referred to as a hydrocarbon doser. However, such electronic control systems and the methods or regimes they execute tend to be slow to react to changing exhaust gas temperatures leading to poor particulate filter regeneration that is longer than necessary and that consumes excessive hydrocarbon fuel. Temperature overshoots are also common where the exhaust gas temperature exceeds a target temperature set by the electronic control system. These temperature overshoots can cause a shut off of the hydrocarbon dosing, which creates a large temperature undershoot characterized by rapid cooling of the particulate filter catalyst. The rapid cooling can crack the particulate filter catalyst and leads to additional delays in achieving complete filter regeneration because the exhaust gas particulate filter must again be brought up to a designated regeneration temperature zone. Moreover, electronic control systems fail to account for partial regeneration events where regeneration has been interrupted due to exhaust gas temperatures falling above or below the designated regeneration temperature zone.